Not Applicable
Not Applicable
1. Field of Invention
This invention pertains to jacking or lifting devices for use with trailers. More particularly, this invention pertains to an apparatus that locates the operator controls at a more convenient height for operation of a conventional lifting jack and thereby assists in the operation of the jack.
2. Description of the Related Art
Generally, lifting jacks are made in many different types and sizes, ranging from small jacking devices used for leveling and supporting work on wood planers to powerful hydraulic jacks capable of lifting a locomotive or even greater weights. The mechanisms used in the different types of jacks also vary greatly, with one of the more popular types consisting of a lifting screw which is inserted in a suitable base.
A common conventional jacking device for use with trailers, automobiles, trucks, campers, and the like includes a vertical member having a base for supporting the jack and an engaging member somehow mounted on the vertical member which may be either attached to, or positioned under the object to be lifted. The engaging member is moved upwardly along the vertical member by way of whatever jacking mechanism is selected, thereby lifting the object. For example, in order to lift the hitching end of a trailer, which is to be attached to a vehicle, the engaging member is fixed to the trailer frame near the hitch, and the engaging member is moved vertically with respect to the vertical member by means of a continuous screw mechanism.
To aid in the use of jacking devices, it is known in the art to have two means of vertical adjustment. A coarse vertical adjustment is used with no load on the jack to bring the base close to the ground. A fine vertical adjustment is used under full load to have the base fully engage the ground surface and to lift the object away from the ground. The use of both a coarse and fine adjustment does away with the need for having to lower or raise the jack by way of a single, slow operating, and continuous jacking mechanism.
One jacking device used with trailers is the type taught in U.S. Pat. No. 4,238,113, entitled xe2x80x9cJacking Device,xe2x80x9d issued to Adams on Dec. 9, 1980. Adams discloses a jacking device for attaching to a vehicle or trailer that has a coarse and fine vertical adjustment. The device of the Adams patent has a telescoping member with a screw mechanism for making fine height adjustments under load and a mounting column for making rough height adjustments in an unloaded state.
Typical of one of the jacking devices currently used with many trailers is the type taught in U.S. Pat. No. 4,796,864, entitled xe2x80x9cSpring Loaded Drop Foot Trailer Jack,xe2x80x9d issued to Wilson on Jan. 10, 1989. The device disclosed in the Wilson patent includes telescoping tubular members that are adjusted vertically by aligning a locking pin between two members for coarse vertical adjustment under no-load conditions and by rotating a screw mechanism for fine vertical adjustment under load. The jack is deployed by allowing one member to drop to a position near the ground, at which point the locking pin is engaged. The screw mechanism is then used to telescope the members such that the lower member contacts the ground and the member attached to the vehicle is lifted away from the ground. Additionally, the Wilson patent claims a means for retracting the member used for coarse adjustment.
Variations of the above type of jack include that disclosed in U.S. Pat. No. 4,978,104, entitled xe2x80x9cQuick Release Jack,xe2x80x9d issued to Gipson, Jr., on Dec. 18, 1990. The jack disclosed in the Gipson patent uses a rack and pinion assembly for vertical adjustment. Coarse vertical alignment of the jack is achieved by disengaging the drive gear from the vertical member, thereby allowing it to travel freely. U.S. Pat. No. 5,755,430, entitled xe2x80x9cTrailer Jack Leveling Adapter,xe2x80x9d issued to Couch on May 26, 1998, discloses a jacking device that has a base with a vertical threaded member extending from it. The threaded member engages a threaded receptor mounted on one of two telescoping tubes. The tubes are fixed in an extended position by a locking pin inserted through aligned holes in the tubes. Operation of this device requires access to the base, which is in contact with the ground.
According to one embodiment of the present invention, a jack assistance apparatus is provided. The jack assistance apparatus allows convenient access to the operator controls of a conventional jack, permitting the jack foot to be lifted without requiring the operator to bend over and grasp the jack foot as it sits on the ground. A lever arm and guide tube is attached to a conventional jack. The conventional jack includes telescoping tubes that have a locking pin for coarse adjustment and a screw mechanism for fine adjustment. The lever arm engages the jack""s locking pin handle and is used to operate the locking pin. The guide tube contains a chain, one end of which is attached to the base and other attached to a ring or other type of handle. When the lever arm operates the locking pin to disengage the telescoping members of the jack, the chain runs free and permits the jack base to drop to the ground, at which time the lever arm operates the locking pin to lock the telescoping members in a fixed vertical position. To lift the base from the ground, the lever arm operates the locking pin to disengage the telescoping members, and a pulling force on the ring or handle causes the chain to transmit a lifting force to the base, which is locked in a raised position by the lever arm operating the locking pin to lock the telescoping members.